Chap. CCXXX.—How to paint a Picture that will last almost for ever.
After you have made a drawing of your intended picture, prepare a good and thick priming with pitch and brickdust well pounded; after which give it a second coat of white lead and Naples yellow; then, having traced your drawing upon it, and painted your picture, varnish it with clear and thick old oil, and stick it to a flat glass, or crystal, with a clear varnish. Another method, which may be better, is, instead of the priming of pitch and brickdust, take a flat tile well vitrified, then apply the coat of white and Naples yellow, and all the rest as before. But before the glass is applied to it, the painting must be perfectly dried in a stove, and varnished with nut oil and amber, or else with purified nut oil alone, thickened in the sun [53].
Chap. CCXXXI.—The Mode of painting on Canvass, or Linen Cloth [54].
Stretch your canvass upon a frame, then give it a coat of weak size, let it dry, and draw your outlines upon it. Paint the flesh colours first; and while it is still fresh or moist, paint also the shadows, well softened and blended together. The flesh colour may be made with white, lake, and Naples yellow. The shades with black, umber, and a little lake; you may, if you please, use black chalk. After you have softened this first coat, or dead colour, and let it dry, you may retouch over it with lake and other colours, and gum water that has been a long while made and kept liquid, because in that state it becomes better, and does not leave any gloss. Again, to make the shades darker, take the lake and gum as above, and ink [55]; and with this you may shade or glaze many colours, because it is transparent; such as azure, lake, and several others. As for the lights, you may retouch or glaze them slightly with gum water and pure lake, particularly vermilion.
Chap. CCXXXII.—Of lively and beautiful Colours.
For those colours which you mean should appear beautiful, prepare a ground of pure white. This is meant only for transparent colours: as for those that have a body, and are opake, it matters not what ground they have, and a white one is of no use. This is exemplified by painted glasses; when placed between the eye and clear air, they exhibit most excellent and beautiful colours, which is not the case, when they have thick air, or some opake body behind them.
Chap. CCXXXIII.—Of transparent Colours.
When a transparent colour is laid upon another of a different nature, it produces a mixed colour, different from either of the simple ones which compose it. This is observed in the smoke coming out of a chimney, which, when passing before the black soot, appears blueish, but as it ascends against the blue of the sky, it changes its appearance into a reddish brown. So the colour lake laid on blue will turn it to a violet colour; yellow upon blue turns to green; saffron upon white becomes yellow; white scumbled upon a dark ground appears blue, and is more or less beautiful, as the white and the ground are more or less pure.